Vacuum formed film topsheets having a silky tactile impression

ABSTRACT

An absorbent article having a topsheet and an absorbent core material. The acquisition distribution layer is located between the topsheet and the absorbent core material. The acquisition distribution layer is made of a three dimensional apertured film that defines a large void volume space between the acquisition distribution layer and the absorbent core material. The acquisition distribution layer provides high void volume for lateral spillage during repeated insult moments because the topsheet, which is in contact with the user, is held away from dispersing fluid that is unabsorbed by saturated core material. The void volume space provides a pathway for unabsorbed fluid to flow over the top plane of saturated core regions to unsaturated regions of the core material for absorption. The void volume space allows this migration of fluid to occur without the fluid coming into contact with the topsheet, thereby avoiding a feeling of wetness for a wearer.

FIELD OF THE INVENTION

[0001] The present invention relates to disposable absorbent products.More particularly, the present invention relates to an apertured, vacuumformed film having properties that give the film a silky tactileimpression or silky feel when the film is stroked by a user.

BACKGROUND OF THE INVENTION

[0002] Advances in film for ring technology have yielded improvements indisposable absorbent products such as disposable diapers, femininehygiene products and the like. “Film” is a common term for thermoplasticpolymer webs made from any variety of processes. The most common methodof producing films is with an extrusion process.

[0003] Cast extrusion and blown extrusion are commonly known methods inthe film producing industry. In a blown extrusion process, a circulardie extrudes an inflated bubble of film that is cooled by cool airstreams blown onto the bubble's perimeter by an air ring. The bubble isthen flattened in a nip and subsequently slit into flat sheets that canthen be reheat embossed or otherwise manipulated. Blown film can be usedto create a roll of precursor film that may be fed into a reheat vacuumformed film (VFF) process. This method is taught by U.S. Pat.No.4,151,240 to Lucas. Additionally, it is also known to use a precursorroll of cast film.

[0004] In a cast extrusion process, a flat web is extruded from a slotdie. The flat web is subsequently cooled and set by a variety ofchilling roller means. As an example, U.S. Pat. No. 4,456,570 to Thomasteaches a cast extrusion in a direct melt vacuum formed film (VFF)process. In a vacuum formed film process, a pressure differential isapplied across a forming screen. In the case of a direct melt VFFprocess, a molten web is extruded onto a forming area of a formingscreen. An example of a direct melt VFF process is taught by U.S. Pat.No. 4,456,570 to Thomas. U.S. Pat. No. 4,151,240 to Lucas teachesreheating and partially melting a web while the web is over the formingarea of the forming screen. A melted polymer is desirable to formthree-dimensional apertures since a melted polymer is more easily suckedinto the apertures in a forming screen. Both U.S. Pat. No. 4,456,570 toThomas and U.S. Pat. No. 4,151,240 to Lucas teach primarily using vacuumas a main source of pressure differential energy that is used for thework energy that changes a two dimensional web into a three dimensionalcell and causes an aperture to open in a film web. During the formationof a VFF, the polymer of the film typically undergoes a phase changefrom molten state in a flat form to a crystalline state in the new threedimensional form.

[0005] In some cases, it is desirable to form textures on the lands ofthe VFF. To form textures on the lands of the vacuum formed film, landsare provided on the forming screen with textures provided thereon. Thetextures on the forming screen are then incorporated into the directmelt VFF film. Due to vacuum pressure, textures form on the lands of thesubsequently formed VFF. As discussed above, the vacuum pressuredifferential also causes 3-D cells with apertures to be formed in thefilm.

[0006] The textures imparted on the VFF may be formed in a pattern.Examples of embossing patterns include straight lines, pyramids,diamonds, squares, and random matte. Further, more exotic patterns maybe used including, exotic squiggly lines, spiral pattens, microscopicflower petals, and other ornamental designs.

[0007] A micropattern can also be incorporated into a precursor film bya reheat VFF process, via either cast embossing or blown embossingprocesses that are well known in the industry and that are discussedabove. In a reheat process, external heat is applied to partially meltand form three dimensional cells with apertures. Portions of theprecursor film rest on the lands of the screen, which partially protectsthese portions of the precursor film from the heat. Therefore, only theportion of the film suspended over an opening of a cell in the formingscreen is fully unprotected from exposure to heat. Thus, the suspendedportion becomes melted and forms a three dimensional cell with anaperture.

[0008] When a film layer is applied to a forming screen, the film layertypically has about 25 to 80 times less mass than a metallic screen massbeneath the film layer. Because of the mass ratio of the film layer tothe screen, the screen acts as a “heat sink” in the land area where theprecursor film is in intimate contact with the lands of the formingscreen. The heat passes through the thin film and is absorbed by thescreen such that no, or negligible, thermal distortion occurs on theland regions. As a result, any texturizing pattern embossed into theprecursor film is maintained in the finished VFF.

[0009] Films produced by the methods above may be constructed of variousmaterials having a selected mesh count, embossed thickness, a selectedaperture pattern, a selected width of the lands or spaces between theapertures, and a selected pattern may be formed on the lands. The “meshcount” is the number of cells aligned in one inch of distance. Othervariations may also be possible. Each configuration will exhibitdistinct properties with respect to performance.

[0010] When measuring a VFF for percent open area, it is common to useany of the many computerized video devices that are available. The videocamera, via magnification and contrast, can discern the openings fromthe lands and digitize the data to calculate the percent open area.

[0011] Unlike nonwoven material (NW), which exhibits capillary actionfor wicking fluids, formed films are made from polymer webs that do nottransmit fluid unless the formed film is “formed” into athree-dimensional apertured sheet. Formed films may be tested for rewet.A lower rewet value is more desirable. Generally, preferred productshave had a rewet value of less than one gram; i.e. a “fractional gram”.It has been found that products with a gram or more of rewet aretypically viewed by consumers as being wet or damp in use.

[0012] Fluid acquisition rate is also critical to a functional topsheet.If the fluid acquisition rate is too slow, then a product using thetopsheet may leak. The fluid acquisition rate is affected by severalfactors. The surface energy of the vacuum formed film is critical forfluid acquisition rate. Additionally, the fluid acquisition rate isdirectly correlated to open area. Additionally, the “loft”, or therequired spacial distance between a fluid containing absorbent core andthe skin of the user, must also have a certain measure to prevent awetness factor of one gram or greater as exhibited by rewet values.Simply stated, if there are relatively large openings, as indicated byhigh % open area, and comparatively little separation space, asindicated by low loft, then fluid can overcome the short expanse ofspace through the center of the large opening, which results in reverseflow, or “rewet”.

[0013] Table 1, below, is derived from selected feminine napkin productsfrom around the world that use a formed film coversheet. From the datain Table 1, the ratio correlation can be seen. From such data, theapparent line of separation of the loft to % open area ratio (L/OARatio) between a “dry” coversheet and “damp” coversheet would logicallybe about a L/OA Ratio of ≧10. TABLE 1 Product Loft, μ Open Area, % L/OARatio Rewet, grams Always 550 32.0 17.0 0.05 Equate 455 28.5 16.0 0.15Siernpre Libre 450 20.0 22.0 0.12 Itimus 370 20.0 18.5 0.10 CareFree 13025.0 5.2 4.85 (Euro) Magix 100 21.5 4.5 6.15 Centre Libre 190 25.0 7.61.90

[0014] The term “rewet” implies that all of the fluid passes through thetopsheet and then only the fluid coming back to the surface to “rewet”it is measured. However, with the many varieties of micro-embossing,crimping, and punching involved with these materials, often “wells” canbe formed that trap fluid on the surface. The entrapped fluid accountsfor about 15% of variation in the data. Also, as with any reliable testmethod, the method itself will have some variation of results, evenwithin a given single material. This is offered to explain why thecorrelation is not exactly linear as, in theory, it should be.

[0015] Hole diameter is determined by the narrowest width of an aperture(specifically for aperturing oval or elliptical shapes) that can bedetermined as a function of mesh count and land width. From mesh countand land width, one can derive an approximate hole diameter, or span ofthe “supports” for the polymer sheet to be apertured.

[0016] A hole diameter of a typically known 60 mesh forming screen isusually no more than 200μ. Since a reasonable amount of metal mustremain between holes in a forming screen (such that it will be robustenough to run in the VFF process), one can calculate hole diameter asfollows. As explained above, “mesh” is the number of cells aligned inone inch of distance; hence, {fraction (1/60)}=0.017 inch center tocenter, or 430μ. One will need about 230μ of metal land area to have arobust screen, leaving the nominal 200μ hole diameter for a 60 meshpattern.

[0017] In addition to rewet performance and fluid acquisitionperformance during use, it has been found that the feel or tactileimpression of a topsheet is important to consumers. Silk has been knownfor centuries to impart a unique and highly desirable tactile impressionthat has no other description than to say, “This feels silky”. The term“silky” alone provides enough description for average global consumersto grasp its meaning and recognize whether or not a product feels“silky” or merely soft and clothlike. In repeated blind panel testsvarious fabrics such as felt, flannel, cotton diapers, polyester/cottonclothing fabric, wool, and silk were tested. The panels easily discern asilky tactile impression (STI) of silk cloth over the other clothmaterials.

[0018] For many years, the feminine napkin market has been segmentedinto women who prefer a nonwoven coversheet and women who prefer a filmcoversheet. The market segmentation is particularly found in westernizedcountries. Those who prefer the nonwoven type seem to prefer theclothlike tactile impression and the perceived “comfort” that theyderive from it.

[0019] Users of the nonwoven type, however, sacrifice the drycleanliness of the VFF type. Nonwovens have capillarity due to havingtheir many fibers in close proximity to the absorbent core. Capillarityis good for transmitting fluid through a coversheet via the capillaryaction of the nonwoven. Unfortunately, “wicking” by capillary action canalso act in reverse. Therefore, nonwovens are not known for providinggood rewet values. A good rewet value is indicative of dry cleanlinessduring use.

[0020] Those who prefer the film type seem to prefer the improvedcleanliness and anti-rewet, particularly that of the VFFs. Many VFFcoversheets have large openings which readily accept semi-coagulatedmatter found in menses. VFFs also provide the afore-mentioned preventionof the fluid rewetting to the top plane of the film. The prevention ofrewet is derived from the superior loft of the VFF material. Hence,those who prefer the prior art film type forgo a bit of clothliketactile impression derived from the presence of fibers of a nonwoven toachieve the cleanliness, which is especially true of a VFF. A film thatdelivers the perceived comfort of a nonwoven with the improvedcleanliness and anti-rewet is desirable. Therefore, much effort has beenmade in attempts to derive the benefits of both types, some with marketsuccess; however, no VFF to date has delivered both the cleanliness anda silky tactile impression.

SUMMARY OF THE INVENTION

[0021] The present invention relates to a vacuum formed film thatdelivers desirable rewet properties and possesses a desirable silkytactile impression or silky feel to a user. In one embodiment, thevacuum formed film has a plurality of cells, wherein the cells areellipse shaped, each having a major axis and minor axis. In anotherembodiment, the cells are boat shaped, wherein the ends on each end ofthe major axis are rounded off. In another embodiment the cells may beoval shaped. Major axes of the cells are aligned in the strokingdirection of the vacuum formed film. The cells define stroking directionlands and a transverse direction lands in areas between the cells. Inone embodiment, the stroking direction lands are raised with respect tosaid transverse direction lands. In yet another embodiment, micro-ridgesare formed on the lands for imparting a silky feel to the vacuum formedfilm. The various film aspects, above, each contribute to the silkytactile impression of the film. In still further embodiments, some orall of the various aspects described above may be combined to achieve afurther improved silky tactile impression. The loft to open area ratioof the vacuum formed film is preferably greater than about 9 andpreferably has a rewet of less than about 1 gram.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a perspective view of a feminine napkin utilizing a filmof the invention.

[0023]FIG. 1A is an plan view of a section of forming screen having anoriented ellipse pattern.

[0024]FIG. 1B is a cross-sectional view of the forming screen of FIG. 1Ataken along line 1B-1B of FIG. 1A.

[0025]FIG. 1C is a cross-sectional view of the forming screen of FIG. 1Ataken along line 1C-1C of FIG. 1A.

[0026]FIG. 2A is a plan view of a second embodiment of a section offorming screen having an oriented ellipse pattern.

[0027]FIG. 2B is a cross-sectional view of the forming screen of FIG. 2Ataken along line 2B-2B of FIG. 2A.

[0028]FIG. 2C is a cross-sectional view of the forming screen of FIG. 2Ataken along line 2C-2C of FIG. 2A.

[0029]FIG. 3 is a plan view of a section of film having an orientedellipse pattern wherein the film has a single plane on all lands.

[0030]FIG. 4 is a plan view of a section of film having an orientedellipse pattern wherein the film has a highest plane on strokingdirection lands.

[0031]FIG. 5A is a plan view of a male side of a section of film havingboat shaped cells.

[0032]FIG. 5B is a plan view of a female side of a section of filmhaving boat shaped cells.

[0033]FIG. 6A is a plan view of a female side of a formed film materialhaving micro-ridges on the lands of the film.

[0034]FIG. 6B is a plan view of a male side of a formed film materialhaving micro-ridges on the lands of the film.

[0035]FIG. 7 is a cross-sectional view of the formed film material ofFIGS. 6A and 6B taken along line 7-7 of FIG. 6B.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Both direct melt and reheat processes are, in this invention,considered to be equivalent methods under the term vacuum formed films(VFF). Since both melt, form, and recrystallize in a three dimensionalshape, each of the processes may be used to form films wherein the loftof the cells are robust. Polymer webs have a property known as “memory”wherein a polymer web will tend to revert to its original shape.Therefore, if a polymer web is formed as a flat web and then forced intoa three dimensional shape without undergoing melting andrecrystallizing, the polymer web will try to revert again to itsoriginal flat shape when any stresses are subsequently applied.Robustness in the third dimension is critical for obtaining and thenmaintaining “loft”, which prevents rewet.

[0037] Two important variables are commonly discussed when describing aVFF, loft and % AO. “Loft” is defined as the top to bottom thickness ofthe vacuum formed film, which is typically the required spacial distancebetween a fluid containing absorbent core and the skin of the user orthe thickness of the vacuum formed film. Loft is typically measured bythe same means used to measure “Embossed Thickness” in the polymer filmindustry. Embossment is merely imparting a third dimension to the film,typically ne with defined pattern and shape. Commonly used devices forthis measurement are called “Low Load Micrometers”. A wide area ofdisplacement with a low compression load is utilized to insure one ismeasuring the full depth of pattern and one is not compressing thepattern to render a false reading. A TMI® Model 49-70 manufactured byTesting Machines, Inc. of Amityville, N.Y. was used for the loftmeasurements herein. This relationship of properties ties directly torewet performance and is a simple calculation of dividing loft, asmeasured in microns (μ), by the percent open area (17.3%, for example).As an example, a packing of 60 mesh round holes on a square patternpacking array, has a percent open area (OA%) that can be calculated asfollows:

OA%={1 inch÷[mesh×mesh (due to square array)]×area of each hole, ininches}×100

A 60 mesh hole is 200μ in diameter, 200μ/25.4μ/mil=7.8 mil or 0.0078inch diameter,

D/2=Radius; hence, Radius (R)=0.0039″

Area=πR ²=0.0039²×3.14159=4.8×10⁻⁵

mesh L×mesh=60×60=3600

{1÷[(4.8×10⁻⁵)×3600]}×100=17.3% Open Area

[0038] For this invention it has been surprisingly discovered that by acombination of pattern, plane and texture, a VFF providing adequate“loft to % open area ratio” for achieving good rewet values can alsoattain a desirable silky tactile impression (STI).

[0039] It has been discovered that STI may be improved by selecting aspecific range of mesh count from about 28 to 60, preferably 40. Iffewer cells exist, it has been found that users can begin to sense theindividuality of cells, which can detract from the STI effect. The STImay be further improved with an oval, boat shaped or elliptical cellhaving a major axis to minor axis ratio of at least about 1.05:1.0 to asmuch as about 6.5:1, more preferably ranging from about 1.5:1 to 4:1.The STI may be still further improved by aligning all the major axessubstantially in the same direction. For purposes of this application,the stroking direction (SD) shall be defined as the direction along alength of an end product, e.g., feminine napkin or the like. FIG. 1shows sample product 5. Arrow 7 shows the stroking direction. Thestroking direction is typically the direction that a consumer strokesthe material when assessing the film. It is desirable to align thestroking direction in a direction most likely to rub back and forthagainst a user during use, i.e. typically in a front to backorientation. By implementing the above steps, a discernable panel testresult may be achieved for STI as compared to other VFF topsheets andsynthetic silk-like nonwoven materials previously known in the art.

[0040] Further, it is commonly understood by those skilled in the artthat the “machine direction” (MD) is the processing direction whenmanufacturing formed films, and with rare exception, when converting theformed film as a topsheet on an absorptive device. The MD is thedirection where the web of the material(s) moves continuously down amachine. As it relates to the forming screens, the MD is thecircumference of the screen and the “Transverse Direction” (TD) is fromthe end to end length of the screen. As is commonly understood, theforming screen rotates around a stationary seal. Therefore, thecircumferential direction is the direction of continuous motion feedingfilm down the machine in the “Machine Direction”. While not typical orcommonly used, alterations from this norm will be understood by a man ofthe art; therefore, these are not intended as limiting to thisinvention.

[0041] On most conversion lines that take the VFF and place it as atopsheet, diapers or pads or bandages or whatever absorptive device isbeing manufactured will align the MD of topsheet down the length, orgreatest dimension, of the product. Especially for feminine napkins, thedifference of length to width is significant. In many tests when napkinsare handed to women, they will typically stroke the topsheet down thelength of the product as shown in FIG. 1. Consequently, it is generallythe case that the stroking direction is synonymous with the machinedirection, although this need not be the case to fall within the scopeof the applicant's invention. For a consumer, the first perceptivetriggers are gained by stroking the topsheet in the fashion describedabove when a consumer desires to know how the product will feel in use.

[0042] The length is also aligned with the anatomy of common disposablearticles. Since disposable articles are typically held in the groinbetween the legs there is little chance of side to side or TD motion. Ifthe product shifts during the natural motions of the user, the shiftwill almost always occur in the MD creating a “stroking” action of thetopsheet against the skin. As explained above, and from all thesecorrelated factors it can be seen that the term “MD” and “SD” aretypically synonymous. The STI effect is gained by a stroking motion.Hence, the reference to the “Stroking Direction” (SD).

[0043] For purposes of this application, the term “oval” shall relate toa rounded shape with a major and minor axis whose lines along the majoraxis direction are essentially curved. The term “ellipse” shall differin that the lines along the major axis direction are essentiallystraight. Hereafter, the ratio of major axes to minor axes shall bereferred to as the SD:TD ratio wherein SD is the stroking direction'salignment of the major axes, and TD is the transverse direction of theminor axes. Although not essential for achieving the STI effect, it hasbeen found that the STI effect is enhanced if the centers of major axesare commonly aligned with each other.

[0044] Again, while not essential for attaining STI effect, the STIeffect may be further enhanced if the lands in the SD are on a slightlyhigher plane than the lands in the TD. Also, the STI can be triggeredwith this step alone. If SD lands are in a slightly higher plane, higherSTI rankings are received when compared to single plane material of thesame configuration. It has been found that as little as 15μ varianceshows a slight distinction, although a 35μ variance is preferred. If afilm has greater than a 145μ variance between the SD lands and the TDlands, then problems can occur with the strength of the forming screen,especially in the case of finer mesh counts. Winding issues, such asroll blocking due to nesting, may be introduced, as well. Since the SDlands are raised, it is less critical to have rounded cell geometries.Many polygonal shapes will also function, such as squares, hexagons,pentagons or other shapes.

[0045] The variance in the height of the planes of the SD land plane andthe TD land plane can be achieved by machining a forming screen withcutting tools, grinding, etching, cutting with energy beams, or affixingwires to alter the external profile of the screen to form bi-planarlands. Additionally, other means may be used for varying the height ofSD lands.

[0046] Also non-essential, but preferred, for increasing the STI effectis the addition of various texturizations to the lands. More preferredis the addition of micro-ridges (MR) of a specific height and spacing.Films having micro-ridges received surprisingly high panel testrecognition of STI when the micro-ridges were applied to films havingmesh counts of 28 or greater and especially to films having a 40 Hexpattern. To form micro-ridge patterns, the pattern is typically etchedinto the land areas of the screen. The micro-ridges will readily form onthe lands of the film, so long as there remains a direct pathway of airevacuation in the spaces between the ridges. The air evacuationrequirement applies to all patterns intended for texturization of thelands of the film. If the molten film lays over a cavity and forms aseal around a perimeter of the cavity, thereby sealing off an airevacuation pathway, the film will be prevented from being suctioned intomicro-pattern depressions. Consequently, the film will be prevented fromconforming to the shape of the micro-pattern depressions.

[0047] All or some of these features and enhancements, e.g, commonlyaligned centers of major axes, elevated SD lands, and micro-ridges, maybe combined to create a VFF material that will exhibit an STI effectamong a majority of panelists assembled to test product. Other importantaspects are maintaining the adequate VFF aperture diameter and productquality for transmission of fluids through the topsheet and into theabsorbent core (especially the more viscous menses fluid), as well asmaintaining the desired “loft to % open area ratio” of the VFF such thatgood rewet values are achievable.

[0048] Additionally, it has been shown that a preferred range of meshcount can contribute to the desired STI. As stated above, mesh count isthe number of cells aligned in an inch of length. The higher the meshcount, the greater the number of cells that are packed together. Thelower the mesh count, the fewer the number of cells in a given linearmeasure and/or square area. Cells or three-dimensional apertures may bepatterned in any of a variety of arrays that are conducive to thedesired objectives. Once an array is chosen, cells can then be countedper an inch of length to determine “mesh”.

[0049] Referring now to FIG. 1A, a section of forming screen 10, whichexhibits an oriented ellipse pattern is shown. In the preferred pattern,ellipse shaped cells or apertures 12 have a major axis 14 and a minoraxis 16. The major axis 14 is aligned in the machine direction (MD),which is indicated by arrow 18. The transverse direction (TD), isindicated by arrow 20. In a preferred embodiment, the ratio of lengthsof major axis 14 to minor axis 16, i.e., “SD:TD” is about3:1.Preferably, all major axes 14 are aligned with each other and arealigned in the machine direction 18. Additionally, all minor axes 16 arecorrespondingly aligned in the TD 20. Areas between cells 12 are SDlands 22 and TD lands 24.

[0050] Referring now to FIG. 1B, a cross-section of forming screen 10 isshown taken along line 2-2 of FIG. 1A. FIG. 1B is an embodiment offorming screen 10 wherein SD land 22 is on a higher plane than TD land24. The SD lands may be seen more clearly in FIG. 1C, which is a crosssection of forming screen 10 taken along lines 1C-1C of FIG. 1A.

[0051] Referring now to FIG. 2A, a section of forming screen 10′, whichexhibits an oriented ellipse pattern is shown. In the preferred pattern,ellipse shaped cells or apertures 12′ have a major axis 14′ and a minoraxis 16′. The major axis 14′ is aligned in the machine direction (MD),which is indicated by arrow 18. The transverse direction (TD), isindicated by arrow 20. In a preferred embodiment, the ratio of lengthsof major axis 14′ to minor axis 16′, i.e., “SD:TD ” is about 3:1.Preferably, all major axes 14′ are aligned with each other and arealigned in the machine direction 18. Additionally, all minor axes 16′are correspondingly aligned in the TD 20. Areas between cells 12 are SDlands 22 and TD lands 24.

[0052] Referring now to FIG. 2B, a cross-section of forming screen 10′taken along lines 2B-2B is shown. FIG. 2B depicts an embodiment whereinan upper surface of SD land 22′ and TD land 24′ are in the same plane.The SD lands may be seen more clearly in FIG. 2C, which is across-section of forming screen 10′ taken along lines 2C-2C of FIG. 2B.

[0053] Referring now to FIG. 3, a single plane VFF 26 is shown. VFF 26is produced from a forming screen having an elliptical pattern with MDalignment of the major axes 28 of cells 30. The pattern shown in FIG. 26is a 40 mesh pattern when counting cells in the TD. Apertures 30 ofvacuum formed film 26 measures about 750μ in the SD or major axis 28direction and about 250μ in the TD or minor axis 32 direction. Thethickness of the cells, which are from top to bottom of thethree-dimensional cells 30, i.e, loft, is about 345μ. The VFF 26 has anopen area of 14.5%. Therefore, the loft to % open area ratio of the VFF26 is about 24. The VFF 26 has a rewet value of 0.08 grams. The variancebetween the upper surface of the SD lands 34 and the TD lands 36 in thebi-planar material 26 is about 20μ.

[0054] Referring now to FIG. 4, a multi-plane VFF 38 is shown whereinthe highest plane is the upper surface of the SD lands 40. VFF 38 isproduced from a forming screen having an elliptical pattern with MDalignment of the major axes 42 of cells 43. The pattern shown in FIG. 6is a 40 mesh pattern. Cells 43 of vacuum formed film 38 measure about750μ in the SD or major axis 42 direction and about 250μ in the TD orminor axis 44 direction. The thickness of the apertures 43, which arefrom top to bottom of the three-dimensional cells 43, i.e, loft, isabout 345μ. The VFF 38 has an open area of 14.5%. Therefore, the loft to% open area ratio of the VFF 38 is about 24. The VFF 38 has a rewetvalue of 0.08 grams. The variance between the upper surface of the SDlands 40 and the TD lands 46 in the bi-planar material 38 is about 20μ.

[0055] Referring now to FIGS. 5A and 5B, FIGS. 5A and 5B show anotherembodiment of VFF that shall be referred to as a VFF having “Boat ShapeCells” (BSC) 50. The “Boat Shaped Cell” embodiment 50 preferably has amesh count of 40. “Boat Shape Cell” refers to the oval shape apertures52 having rounded tips. Apertures 52 have a major axis 54 and a minoraxis 56. Preferably, the ratio of length of major axis 54 to minor axis56 of the cells is about 1.75:1. It has been found that rounding off theextremities of either an oval shaped cell, as shown in FIGS. 5A and 5B,or an ellipse shaped cell, as shown in FIGS. 3 and 4, further enhancesthe STI, especially in a single plane material. The BSC embodiment 50 ofFIGS. 5A and 5B has cells 50 having a length along the major axis 54 ofabout 425μ and a length along the minor axis of about 240μ. The BSC film50 has a loft of 315μ and an open area of 22%, which yields a loft to %open area ratio of 14 and a rewet value of 0.15 grams. Of course, theabove dimensions are illustrative and other dimensions of may be used.

[0056] An additional feature of the BSC embodiment 50 is that the majoraxis 54 of the boat shaped cells or three dimensional apertures 52 arealigned in the SD but are not commonly aligned with each other, i.e.,the cells 52 are presented in a “staggered” arrangement. Consequently,SD lands 58 are not straight as is the case with SD lands 34 (FIG. 3)and 40 (FIG. 4) of VFF films 26 and 38, respectively. A film havingbi-planar lands, e.g, the embodiment shown in FIGS. 1A and 1B, are notpreferred for the staggered BSC embodiment because it has been foundthat bi-planar lands are best achieved when all the SD lands, e.g. 34and 40 are co-aligned with each other. Despite these less preferredvariations, it has been found that panelists have still been able toderive a noticeable STI from the 40 mesh BSC (when counting the mesh inthe TD) embodiment 50. Application of a random matte texture to thelands further enhances the material and slightly improves a panel's STIrating of the material.

[0057] While it is known that the addition of any of the aforementionedVFF-capable textures to the lands will contribute to improvement of thetactile impression and eliminate any perceptive triggers that areindicative of a plastic type material, it has surprisingly been foundthat “micro-ridges” (MR) alone can create a perceptible STI. Referringto FIGS. 6A, 6B and 7, microphotographs of a top view of VFF 100 (theside to the user; FIG. 6A) and a bottom view of VF 100 (the side awayfrom the user; FIG. 6B), and an expanded graphic in cross-section of VFF100 (FIG. 7) are given to show the MR of this invention. VFF 100 has a40 hex pattern. To form textures on lands 102 of VFF 100, lands on aforming screen that is used to make VFF 100 are ground to besubstantially flat to accept the artwork for etching the micro-ridges inthe land region of the forming screen. As a result, lands 102, formedbetween apertures 104, are imparted with micro-ridges 106. The machinedirection (MD) or stroking direction (SD) is indicated by arrow 108.

[0058] Micro-ridges 106 preferably have individual distinction with arange of height and spacing and have an optimum STI effect when alignedon a bias, i.e., at offset angle 110 to the SD 108. Offset angle 110 maybe 5° to 80° to achieve some effect, but the preferred range for offsetangle 110 is from 30° to 60° and ideally 45° is used. The height of theMR 106 can range from 5μ to 75μ, but the preferred range is from 5μ to35μ. Ideally, MR 106 have a height of 20μ. Spacing between micro-ridges106 can range from 25μ to 250μ, but more preferably range from 50μ to150μ. Most preferably, a 95μ spacing is used. The micro-ridges 106 mustalso maintain “individuality”. If micro-ridges 106 becomeinterconnected, then micro-ridges 106 will not create the desired STIbut rather the micro-ridges 106 will exhibit a planar and plastic-likefeel instead.

TEST DATA

[0059] Various formed films were tested by ten panelists for silkytactile impression (STI). The results are presented in Table 2, below.The panel method was based upon the AATCC (1997) Evaluation Procedure 5,Fabric Hand: Guidelines for the Subjective Evaluation of Fabric, aTechnical Manual of the American Association of Textile Chemists andColorists. Volume 72 (pp.352-354). Research Triangle Park. NC: and. ASTM(1968) Manual on Sensory Testing Methods. ASTM Special TechnicalBulletin 434, 1968. pp.3-5.

[0060] The evaluation procedure utilized a common pad of standardthickness and material yielding a standard compressibility. Values forthickness and compressibility are not particularly important, so long asthe values are consistent. The pad was cut into 1.5×3.0” rectangles. Thefilms were wrapped fully around and taped closed, much like wrapping agift, leaving on one side a continuous, smooth area of material. Thecontinuous, smooth side comprise the tested side. Panelists washed theirhands so that the samples were not tainted; tainting potentiallycreating an anomalous variance between panelist one and panelist ten, asthe samples are passed from one panelist to another.

[0061] The samples were coded by an identifier, such as a number orletter, but no information was provided to avoid any pre-biasing of apanelist. The panelists were asked to rate the samples from 1 to 10 with1 being the silkiest and 10 being not silky.

[0062] All but one of the products in the test data of Table 2 below areapertured film embodiments, except for “Unicharm's TS Threads on NW”.The Unicharm product is not a formed film product, but it has been addedto Table 2 because it is recognized as succeeding as a feminine napkintopsheet in Asia and is known to be viewed as triggering a favorableSTI. It is constructed by an unknown method wherein synthetic silkthreads are bonded to a top plane (skin contact side) of a nonwoven web.Holes are punched through the material, apparently to increase the rateof fluid acquisition. Its fluid acquisition rate value is believed to beover 3.0 grams. The Unicharm product is included here to assist inobtaining a stronger reading on the panel test's apparent line ofseparation between STI and non-STI materials. Also included for thatpurpose is Comfort Silk®.

[0063] Comfort Silk® is a mechanically formed apertured film but is nota VFF. It too has been accepted as “Silky” in the marketplace.Therefore, the inclusion of Comfort Silk® aids in making STI and non-STIdistinctions.

[0064] In reviewing the data, it is commonly accepted that an averageranking of a film by ten panelists of a value of ≦5.0 indicates a STI isdiscernable. The number of No. 1 rankings given by panelists can alsoserve as an indication that an STI has been ‘triggered’. TABLE 2 40 HexUnicharm's FlatLand TS w/Micro Threads Testers MD Ellipse Ridges 40 BSCon NW Comfortsilk Always Equate 1 6 3 2 5 1 8 10 2 4 1 3 7 2 10 6 3 1 24 5 3 9 10 4 2 1 6 3 5 8 10 5 3 1 6 4 5 10 8 6 5 1 3 6 2 9 7 7 1 4 7 6 35 10 8 2 1 6 4 5 8 10 9 6 1 5 4 2 10 8 10 5 3 1 6 2 9 10 AVG. 3.5 1.84.3 5 3 8.6 8.9

[0065] Another important test for comparing various films is a “RewetTest”. For testing rewet a test fluid comprising two parts Pepto-Bismol®and one part distilled water was used. The sample assembly consisted ofa 5×5 inch piece of vacuum formed film or nonwoven topsheet placed withthe user side up and the garment side down over 3 plies of absorbentmedium. An amount of 2-ml test fluid was delivered through a pipetteonto the center surface of the topsheet. The time, in seconds, taken forall of the liquid to penetrate through the topsheet was recorded with astopwatch. This portion of the test indicates the fluid acquisitionrate. After the initial insult, an additional 15-ml of the test fluidwas delivered to the center surface of the topsheet. An 8 lbs rewetweight with a 4×4 inch footing was placed on the top of the topsheet for3 minutes for the fluid to thoroughly spread out into the core pads.Then, two pre-weighted pickup papers were pressed against the topsheetwith the 8 lbs rewet weight for an additional 2 minutes. The amount ofweight increase of the pickup papers was measured in grams as the rewetamount, which reflects the amount of fluid that successfully reversedflow and overcame the spatial separation of the topsheet material.. Ithas been found that data using this fluid for both acquisition rate andrewet values correlates well to comparative data generated from the sameVFF materials tested by this method and by undisclosed methods used bymajor corporations who produce feminine napkin products.

[0066] Table 3, below, compares existing products and shows thatembodiments of this invention provide a desirable STI, and also maintaina L/OA Ratio that exhibits functional rewet: TABLE 3 Open Area, Rewet,Product Loft, μ % L/OA Ratio grams STI (Y/N) Always 550 32.0 17.0 0.05 NEquate 455 28.5 16.0 0.15 N ComfortSilk 115 28.5 4.0 1.25 Y SD Ellipse345 14.5 23.8 0.08 Y 38 40 Mesh 315 22.0 14.3 0.15 Y BSC 50

[0067] It is thus believed that the operation and construction of thepresent invention will be apparent from the foregoing description. Whilethe apparatus and compositions shown or described have beencharacterized as being preferred it will be obvious that various changesand modifications may be made therein without departing from the spiritand scope of the invention as defined in the following claims.

What we claim is:
 1. A vacuum formed film comprising: a plurality ofcells, wherein a majority of said plurality of cells have a major axisand minor axis; wherein substantially all of said major axes of saidplurality of cells are substantially aligned in a stroking direction ofthe vacuum formed film; and a loft to open area ratio of the vacuumformed film is greater than about
 9. 2. The vacuum formed film accordingto claim 1 wherein: the vacuum formed film has a rewet of less thanabout 1 gram.
 3. The vacuum formed film according to claim 1 wherein:said plurality of cells define stroking direction lands and transversedirection lands in areas between said plurality of cells; and at least aportion of said stroking direction lands are raised with respect to saidtransverse direction lands.
 4. The vacuum formed film according to claim1 wherein: said plurality of cells define lands in areas between saidplurality of cells; and micro-ridges are located on said lands forimparting a silky tactile impression to the vacuum formed film.
 5. Thevacuum formed film according to claim 1 wherein: the vacuum formed filmhas a mesh count of greater than approximately
 25. 6. A vacuum formedfilm comprising: a plurality of cells wherein a majority of saidplurality of cells have a major axis and minor axis; and whereinsubstantially all of said major axes of said plurality of cells aresubstantially aligned in a stroking direction of the vacuum formed film.7. The vacuum formed film according to claim 6 wherein: a loft to openarea ratio of the vacuum formed film is greater than about
 9. 8. Thevacuum formed film according to claim 6 wherein: wherein the vacuumformed film has a rewet of less than about 1 gram.
 9. The vacuum formedfilm according to claim 6 wherein: said plurality of cells definestroking direction lands and transverse direction lands in areas betweensaid plurality of cells; and at least a portion of said strokingdirection lands are raised with respect to said transverse directionlands.
 10. The vacuum formed film according to claim 6 wherein: saidplurality of cells define lands in areas between said plurality ofcells; and micro-ridges are located on said lands for imparting a silkyfeel to the vacuum formed film.
 11. The vacuum formed film according toclaim 6 wherein: the vacuum formed film has a mesh count of greater thanapproximately
 25. 12. A vacuum formed film comprising: a plurality ofcells, wherein a majority of said plurality of cells have a major axisand minor axis; wherein substantially all of said major axes of saidplurality of cells are substantially aligned; and wherein the vacuumformed film has a rewet of less than about 1 gram.
 13. The vacuum formedfilm according to claim 12 wherein: a loft to open area ratio of thevacuum formed film is greater than about
 9. 14. The vacuum formed filmaccording to claim 12 wherein: said major axes of said plurality ofcells are substantially aligned in a machine direction of the vacuumformed film.
 15. The vacuum formed film according to claim 12 wherein:said plurality of cells define stroking direction lands and transversedirection lands in areas between the cells; and wherein at least aportion of said stroking direction lands are raised with respect to saidtransverse direction lands.
 16. The vacuum formed film according toclaim 12 wherein: said plurality of cells define lands in areas betweensaid plurality of cells; and micro-ridges are located on said lands forimparting a silky tactile impression to the vacuum formed film.
 17. Thevacuum formed film according to claim 12 wherein: the vacuum formed filmhas a mesh count of greater than approximately
 25. 18. A vacuum formedfilm comprising: a plurality of cells defining stroking direction landsand transverse direction lands in areas between said plurality of cells;and wherein a majority of said stroking direction lands are raised withrespect to said transverse direction lands.
 19. The vacuum formed filmaccording to claim 18 wherein: a loft to open area ratio of the vacuumformed film is greater than about
 9. 20. The vacuum formed filmaccording to claim 18 wherein: at least a portion of said plurality ofcells have a major axis and minor axis; and wherein said major axes ofsaid plurality of cells are substantially aligned in a strokingdirection of the vacuum formed film.
 21. The vacuum formed filmaccording to claim 18 wherein: at least a portion of said plurality ofcells have a major axis and minor axis; wherein said major axes of saidplurality of cells are substantially aligned; and wherein said vacuumformed film has a rewet of less than about 1 gram.
 22. The vacuum formedfilm according to claim 18 wherein: micro-ridges are located on saidlands for imparting a silky tactile impression to the vacuum formedfilm.
 23. The vacuum formed film according to claim 18 wherein: thevacuum formed film has a mesh count of greater than approximately 25.24. A vacuum formed film comprising: a plurality of cells defining landsin areas between said plurality of cells; and micro-ridges located onsaid lands for imparting a silky tactile impression to the vacuum formedfilm.
 25. The vacuum formed film according to claim 24 wherein: a loftto open area ratio of the vacuum formed film is greater than about 9.26. The vacuum formed film according to claim 24 wherein: at least aportion of said plurality of cells have a major axis and minor axis; andwherein said major axes of said plurality of cells are substantiallyaligned in a stroking direction of the vacuum formed film.
 27. Thevacuum formed film according to claim 24 wherein: at least a portion ofsaid plurality of cells have a major axis and minor axis; said majoraxes of said plurality of cells are substantially aligned; and saidvacuum formed film has a rewet of less than about 1 gram.
 28. The vacuumformed film according to claim 24 wherein: said plurality of cellsdefine stroking direction lands and transverse direction lands in areasbetween said plurality of cells; and wherein at least a portion of saidstroking direction lands are raised with respect to said transversedirection lands.
 29. The vacuum formed film according to claim 24wherein: the vacuum formed film has a mesh count of greater thanapproximately
 25. 30. A vacuum formed film comprising: a plurality ofcells, wherein a majority of said plurality of cells have a major axisand a minor axis; wherein substantially all of said major axes of saidplurality of cells are substantially aligned; and the vacuum formed filmhas a mesh count of greater than approximately
 25. 31. The vacuum formedfilm according to claim 30 wherein: a loft to open area ratio of thevacuum formed film is greater than about
 9. 32. The vacuum formed filmaccording to claim 30 wherein: said major axes of said plurality ofcells are substantially aligned in a stroking direction of the vacuumformed film.
 33. The vacuum formed film according to claim 30 wherein:the vacuum formed film has a rewet of less than about 1 gram.
 34. Thevacuum formed film according to claim 30 wherein: said plurality ofcells define stroking direction lands and transverse direction lands inareas between said plurality of cells; and at least a portion of saidstroking direction lands are raised with respect to said transversedirection lands.
 35. The vacuum formed film according to claim 30wherein: said plurality of cells define lands in areas between saidplurality of cells; and micro-ridges are located on said lands forimparting a silky tactile impression to the vacuum formed film.